When attaching a prosthetic limb to an amputee's residual limb, a thermoplastic socket having a cavity shaped to receive the residual limb is typically fitted over the residual limb, and the prosthetic limb is typically joined to the bottom of the socket using an attachment plate. The socket can be held in place on the residual limb using the Vacuum Assisted Socket System (VASS)™, developed by Otto-Bock HealthCare LP and described in U.S. Pat. Nos. 6,761,742 and 6,926,742, the disclosures of which are incorporated herein by reference. FIGS. 1 and 2 show two embodiments of a Vacuum Assisted Socket System (VASS) socket and attachment plate joined to a prosthetic limb, according to the prior art. The socket 12 fits over the patient's residual limb 14 and is held in place by a vacuum seal formed by evacuating air from the space between the socket 12 and the residual limb 14. The socket features an attachment plate 16 on its bottom end for joining the socket to the hardware of the prosthetic limb 18. The structure and function of the Vacuum Assisted Socket System (VASS) depicted in FIGS. 1 and 2 are described in U.S. Pat. No. 6,926,742.
In a dual socket system (double wall socket system), an inner socket is fitted to the patient's limb, while the pylon assembly is attached to an outer socket. The outer socket slides over the inner socket. The two sockets are typically held to each other by some mechanical means, such as a latch. The inner socket is fabricated to fit precisely around the patient's residual limb. It is held to the patients residual limb by some mechanical means, such as a vacuum. The outer socket is formed to accept the inner socket and any additional components associated therewith in proper alignment and then laminating the outer socket over the mold. The outer socket has traditionally been formed by fabricating a temporary mold on the distal end of the inner socket to create the proper spacing and alignment. This process is labor intensive, can be imprecise, and often requires fabrication at a central location in a specialized facility.
There is a need for a standardized method that saves labor, helps to ensure appropriate alignment, and allows for fabrication at decentralized locations.